The field of the invention relates to testing of blood samples and more particularly to devices for testing hemostasis.
Methods of measuring the coagulation characteristics of blood are known. Some such devices attempt to simulate the natural flow of blood in the veins and arteries of a living subject.
An accurate measurement of the ability of a patient""s blood to coagulate in a timely and effective fashion is crucial to certain surgical and medical procedures. Accelerated (rapid) and accurate detection of abnormal coagulations is also of particular importance with respect to appropriate treatment to be given to patients suffering from clotting disorders. Often the condition of such patients makes it necessary to administer anti-coagulants, certain fibrinolytic agents, anti-platelet agents, or blood components in a quantity which may only be determined after taking into account the abnormal components or xe2x80x9cfactorsxe2x80x9d of the patient""s blood which may be contributing to the clotting disorder.
One measure of blood clotting is provided by the Thromelastograph (TEG(copyright)) Coagulation Analyzer manufactured by Haemoscope of Skokie, Ill. The Haemoscope device measures the mechanical properties of the clot throughout its structural development.
A number of references describe instruments for measuring blood clotting characteristics based upon simple mechanical movements. These instruments monitor the elastic properties of blood as it is induced to clot under a low shear environment resembling sluggish venous blood flow. The patterns of change in shear elasticity enable the determination of the kinetics of clot formation, as well as the strength and stability of the formed clot. The strength and stability of the clot provide information about the ability of the clot to perform the xe2x80x9cwork of hemostasisxe2x80x9d (i.e., stop or prevent abnormal bleeding) and about the adequacy of blood platelet-fibrin interaction. The kinetics of clot formation provide information about coagulation factors available for clot formation. Analysis of the information provides results which are useful to predict bleeding, to monitor and manage thrombosis, and to monitor fibrinolysis.
While the instrument of the reference is effective in measuring hemostasis based upon resistance to mechanical movement, the apparatus necessary to cause movement and torque measurement is unnecessarily complex. The apparatus is even more difficult to load and unload. Because of the importance of measuring blood clotting, a better apparatus for measuring hemostasis is needed.
A method and apparatus are provided for measuring hemostasis. In one embodiment, the apparatus includes a torque sensing column having a torque sensing element and a drive ring disposed around a body of the column and in registration with the column so as to allow rotation of the drive ring around a longitudinal axis of the column. The embodiment further includes a first guide shaft rigidly secured to the drive ring, the guide shaft extending parallel to the longitudinal axis of the column and a cup holder movably attached to the guide shaft, allowing the cup holder to move parallel to the longitudinal axis of the column. The embodiment also includes a sample cup assembly adapted to engage the cup holder on an outer surface and the torque sensing element of the torque sensing column on an inner surface.
The apparatus includes novel features which allow for the quick and easy replacement of blood samples. A unobstructed front surface of the apparatus allows the operator better access for easier cup and blood sample placement. A control lever on a torque measuring column of the apparatus allows a pin of the sample cup assembly to be quickly and easily ejected. The sample cup holder may be lifted to a convenient position and a button on the bottom of the holder activated to release the sample cup assembly for easy removal.